Chromate inhibitors have long been the choice for corrosion protection of metals, such as steel, aluminum, iron, copper, alloys thereof, and the like. The commonly used chromate corrosion inhibitors, such as strontium chromate and barium chromate, are very slightly soluble and, as a result, are highly useful as pigments in paints or primer coatings, which are applied to metal surfaces. Although these pigments can be very effective in controlling the corrosion of metals, the resulting chromate ions are carcinogenic and toxic and, therefore, environmentally unfriendly and harmful to one's health.
Due to these hazards, the Environmental Protection Agency has mandated the elimination of chromate pigments. As such, there is an urgent need for the paint and pigment industries to seek an equally effective and environmentally benign corrosion inhibitor. However, a chromate-substituted inhibitor, such as for use in paints or primer coatings, has been a great challenge because of the high, i.e. quick, solubility of effective chromate replacements.
Accordingly, there is thus a need for a slow-release corrosion-inhibitor useful for coating metal surfaces, such as by way of a paint or primer coating, to effectively control corrosion thereof and that may be less carcinogenic and less toxic than chromate corrosion inhibitors.